An audio device that plays back a sound signal such as music is usually installed for use in a room in a house. The audio device includes a loudspeaker and a playback device which is provided with one or more of a compact disc (CD) player, a media server device, and an amplifier. In the room where the audio device is installed, an installment position of the loudspeaker is limited according to a style of the room, a shape and arrangement position of furniture, and the like, or the position of a user listening to a sound played back by the audio device is changed. The acoustic characteristics, for example, frequency characteristics, of the sound output through the loudspeaker and reaching the ears of the user vary according to the style of the room, the shape and arrangement of furniture, and the like.
When a sound signal is played back by the audio device, it is desirable that an intended sound is provided to the user by the audio device with less influence on the sound due to the installment position of the loudspeaker in the room where the audio device is installed and the position of the user listening to the sound played back by the audio device. However, the intended sound may not be reproduced due to the style of the room where the audio device is installed, furniture, and the like.
There is a disclosure of a technique for measuring frequency characteristics of the room using a microphone which is specialized for measurement and which has known characteristics, and correcting frequency characteristics of a playback device based on the frequency characteristics of the room such that an intended sound reaches a user. Measurement of frequency characteristics needs arithmetic processing such as frequency analysis. An audio video (AV) amplifier having incorporated therein a high-performance digital signal processor (DSP) for executing such arithmetic processing has been commercialized.
For example, PTL 1 discloses a method and device for measuring an impulse response for measuring transmission characteristics of a measured system such as an acoustic device, an acoustic space, and a transmission line for an electric signal.